Buckle for a strap



Sept. 24, 1968 E. CURRAT 3,402,439

BUCKLE FOR A STRAP filed June 29, 1966 F/G.3 I

United States Patent 3,402,439 BUCKLE FOR A STRAP Emile Currat, Geneva, Switzerland, assignor to F. Baumgartner S.A., Geneva, Switzerland, a

ABSTRACT OF THE DISCLOSURE A buckle for securing a nonperforated strap by wedging the strap between a spring-loaded locking device pivotably mounted in a frame member and a first end portion of the frame member. The locking device is free to swing into and out of the plane of the frame member in one direction, but is prevented from swinging in the other direction by means of a stopping device within the frame member. In securing a strap, the free end of the strap presses under the first end portion of the frame member, over the spring-loaded locking device, and under a second end portion of the frame member. The locking device is provided with a friction-producing terminal portion which is positioned beneath the first end portion, and the strap is thereby wedged between the locking device and the first end portion.

The object of the present invention is a buckle for a strap such as a belt or bracelet, and in particular for a watch bracelet or strap, said buckle comprising a frame on which is hooked one end of the strap while the free end of the strap passes under a cross-member of the frame.

Summary of the invention The buckle is characterized by the fact that it comprises -a locking device hinged on the said frame and capable of being raised out of the plane of the frame and of being returned substantially into the said plane, to rest on stop means, the said locking device being composed of two parts which are slidable relative to one another and which a resilient device tends to maintain in relatively extended positions, the whole arrangement being such that, when the free end of the strap is engaged under the cross-member with the locking element in the raised position, the latter can then be returned to engage over the cross-member and to be locked by the action of the said resilient device, the locking element then resting on the said stop means and partially reassuming its extended position, so as to press the free end of the strap against the cross-member and to produce a pinching effect at its end part.

Brief description of the drawing The invention will be described more fully with reference to the accompanying drawing which show, by way of example only, one embodiment of the invention. In the drawing:

FIGURE 1 is a view in perspective of a buckle for a wristwatch strap;

FIGURE 2 is a longitudinal sectional view of the buckle, shown with a strap in place.

FIGURE 3 is a plan view of a detail, partially sectioned, on a larger scale.

The buckle shown comprises a frame 1 on to which there is hooked by means of a small cross-bar, one end designated 3a, of a watch strap. At each end, the frame comprises a cross-member 1a or 111, respectively under 3,402,439 Patented Sept. 24, 1968 which the other end of the strap, designated 3b, passes when the buckle is closed.

In addition, the buckle comprises a locking device composed of two parts, 4 and 5, sliding relative to each other. The part 4 consists of a flattened tubular sleeve, of rectangular cross-section, in which the rear end of part 5 engages. The width of the sleeve 4 corresponds to the space separating the two sliding parts, designated 10, of the frame 1. The part 4 of the locking device encloses a bar 6 of rectangular section, parallel to the cross-bar 2 and to the cross-members 1a and 1b and ending in two short pins 6a pivoting in the sides 1a of the frame. The part 4 of the locking device is engaged with the bar 6 at 4a. It encloses three coil springs 7, parallel to each other and engaged partly in sockets 8 formed in the part 5 and partly in depressions 9 provided in bar 6 (FIGURE 3). Two lateral clasps 4b at the outer end of the part4 of the locking device engage two lateral shoulders 5a on part 5, thereby preventing the latter from separating from part 4 under the action of springs 7 which tend to push parts 4 and 5 apart.

The free end, designated 5b, of the end part 5 of the locking device is backwardly directed and has grooves 10 of sawtooth cross-section, intended. to increase the grip on the end 3b of the strap.

The locking piece comprising parts 4, 5 is pivotable about the axis of bar 6 and can assume a position in which it is raised out of the plane of the frame 1 (FIG- URE 1) and a position in which it is returned within the frame (FIGURE 2) to rest on two stops 1d on the sides of the frame.

The buckle operates in the following manner:

When the locking device 4, 5 assumes its raised position, the free end 3b of the strap is engaged under the outer cross-member 1a of the frame. The locking device is then returned to a position in the plane of the buckle. In the course of this movement it engages over the crossmember 1a and is compressed against the action of springs 7, then partially reassumes its extended position as it comes to bear against the stops 1d. The tip 5b of its end part 5 is then pressing the end 3b of the strap against the cross-member 1a, with a pinching eifect; when the locking device is in this position, the tip of end part 5 which is backwardly directed is substantially parallel to the end 3b of the strap, so that several of the grooves cooperate with end 3b.

It is to be noted that the locking action is not primarily produced by springs 7, the essential purpose of these springs being to engage the end 31) of the strap' with the part 5 of the locking device. The pinching action of the part 5 of the locking device produces a self-locking effect, which is increased by the tension to which the strap is subjected.

In a modification of the above-described form of buckle, the coil springs 7 are replaced by a leaf spring folded accordion fashion, occupying the whole width of the interior of the tubular part 4 of the locking device.

Another modification would be for the grooves 10 in the tip 5b of the part 5 of the locking device to possess a form different from the sawtooth section shown, or for same to be omitted altogether.

What I claim is:

1. A strap buckle comprising a frame having two cross members; a locking device including two parts, a first part pivotably secured to the frame adjacent one of said cross-members and movable in and out of the plane of the frame and a second part slidably mounted within said first part, resilient means within said first part acting upon said second part for urging the two parts away from one another, said first and second parts including means for arresting the movement of said second part away from said first part; stop means in said frame for limiting the pivotal movement of the locking device; said second part of the locking device including a terminal backwardly directed end portion which, when said second part is fully displaced by the action of the resilient means, is disposed beneath the other of said cross-members; said one cross member being adapted to secure one end of a strap, the other end of the strap passing under the other of said cross-members, then over said locking device and finally under said one cross-member, said strap thereby being wedged between the backwardly directed end portion of said second part and the other of said cross-members.

2. A buckle as claimed in claim 1 wherein said resilient means comprises at least two coil springs parallel to one another, said first part of the locking device is provided with depressions engaging ends of said coil springs and said second part of the locking device is provided with sockets engaging opposite ends of the coil springs.

3. A buckle as claimed in claim 1 wherein said resilient means comprises a leaf spring folded accordion fashion.

4. A buckle as claimed in claim 1 wherein said means for arresting the movement of said second part away from said first pa-rt comprises a pair of lateral shoulders on said second part which are eng-ageable with a pair of ridges provided in said first part.

5. A buckle as claimed in claim 1 wherein the backwardly directed end portion of said second part has a sawtoothed profile for enhancing the wedging of the strap between the backwardly directed end portion of the second part and the other of said cross-members.

6. A buckle as claimed in claim 1 wherein the frame comprises side members defining with the cross-members a space and wherein the locking device is as wide as said space.

7. A buckle as claimed in claim 1 wherein the backwardly directed end portion is substantially parallel to the strap wedged between said backwardly directed end portion and the other of said cross-members when the strap is locked into position.

References Cited UNITED STATES PATENTS 946,917 1/1910 Hubbard 24194 3,204,314 9/1965 Sokoloff 24188 FOREIGN PATENTS 17,602 1887 Great Britain. 367,793 2/ 1939 Italy.

BOBBY R. GAY, Primary Examiner.

E. SIMONSEN, Assistant Examiner. 

